Carbon and graphite electrodes can be made by incorporating calcined coke derived from coal or petroleum, lamp black, thermal carbon black, graphite and the like in a binder which coats the surface of the particles. The pastelike mixture subsequently is extruded into desired electrode lengths which then are slowly baked at temperatures up to about 2000.degree. F., until the electrodes assume a hard condensed structure. They may be further treated at temperatures above 4500.degree. F., to graphitize them.
In the extrusion process prior to baking the electrodes, the incorporation of a lubricant onto the working surfaces of the extrusion die ordinarily is necessary to ensure producing electrodes having a continuously exterior smooth surface. In the past, residues of vacuum distilled paraffinic crude oils such as the Pennsylvania type have been used as carbon extrusion oils. However, many of these residues, because of their high concentration of aromatic and naphthenic fractions, have not proved suitable. They have, at times, proved to be too miscible with the green extruded carbon pieces.
An object of this invention, therefore, is to provide a new and improved carbon extrusion oil. Still another object of this invention is to provide an improved process for the manufacture of carbon electrodes.